Rayfoss Blu-Ray laser diode driver review

[lazerov]

Seeing there aren't any reviews for this driver I decided to write my first one.

Here is the link to the site: Rayfoss
Edit: As of 01.07.2010 this driver is not available.
You can find pictures of the driver along with pin out, there.
The site is down at this time, so here is a picture:

I have four of these drivers. Three of them are currently used. One of them drives a PHR@100mA from 2xAAA power source. Other two are powering a 4x and SF-AW210 blu-ray LDs at 160mA and 180mA respectively. They are both supplied by one RCR123 3,6V li-ion battery.

One thing somebody who is going to use this driver has to note is that this driver uses a fixed resistor to set the output current. This is good for me because using a potentiometer might result in some problems (like accidental wrong current setting) but it may present some difficulty to members who have no experience soldering SMD components. It is possible to ask for the proper resistor when ordering. Approximate resistor values for different output currents are: 1.2Ohm for 100mA, 1Ohm for 120mA, 0,68Ohm for 180mA. The resistor value can be calculated through dividing 120 by the desired output current.

There is a minor flaw in the design of this driver which results in spikes in the output voltage. It is easily fixed using a small 47~100nF SMD cap between the + and - output terminals. I'm going to write a mail to Rayfoss about this issue soon.
Picture showing how to connect the filter capacitor:

Some technical data (stated):
Input voltage: 3.0V to 5.5V
Output current: 50mA to 160mA
Dimension: 9x20mm (without spring)

I have used this driver with input voltage down to 2,7V and it still worked properly. It can supply more than 160mA, I've tried up to 200 but I'd not recommend more than 180mA.

Now the most important part - the testing
I did thoroughly test this driver with current setting resistor value of 1Ohm. I used variable power supply. Had to use also a total of 4 meters. Test load was made using 6x1N4005 diodes. Note that values in this table are taken after PCB reached thermal stability, e.g. hot! So current is about 10mA lower than usual. There may be up to 2-3% error in measurements.

As you can see the efficiency is not that great. So this small PCB has to dissipate a lot of heat. The output current is a bit dependent on the input voltage. It also changes during heat up of the driver.

Pros:

• Wide input voltage range. Can use 2/3xNi-MHs 2/3xAlkalines or 1 Li-ion battery.
• Cheap - $6. Maybe the cheapest boost driver for laser diode available.
• Uses fixed resistor to set the current (also a con)

Cons:

• Not the best efficiency available.
• Has spikes in the output voltage (easy to fix)
• Output current is not rock stable over the entire input voltage range.

In short, I would recommend this driver for use with PHR or 4x diodes. But seeing how most people here push their 6x diodes over 200mA it's not good for a 6x blu-ray.

 

[bobhaha]

Awesome review man A++ great explination!! I was waiting for you to get your shipment and for your review! this is a great little dirver for a PHR build but i wouldn't trust it with anything more expensive/sensitive!

+rep for review man! -Adrian

 

[lazerov]

Thank you, Adrian!

this is a great little dirver for a PHR build but i wouldn't trust it with anything more expensive/sensitive!

I fully agree with this ... even though I have one of them driving a sf-aw210. There is risk of overheating the driver.

I was waiting for you to get your shipment

I have to admit I have no idea about which shipment you are talking about :wtf:

Anyway here is a picture of some modules utilizing this driver + unused driver along with a DX green module.

 

[bobhaha]

The shipment of drivers.. on another thread (IIRC the DC/DC boast thread) you said you were going to order a few of these drivers and give a review.. I was waiting for this review!

 

[Tabish]

Awesome review !!!!!!!!!!!

You saved all of us sooo much trouble lol

Can't wait to get mine. It ships tomorrow! Perfect for my PHR.

300mA draw is pretty good when using 2 x 1.5v AAA

EDIT: Anyone know where I can get the 47nF caps for cheap ??? (they have to be very small)
I don't have an electronics shop nearby

 

[bobhaha]

Well its an electronic component.. don't think your going to find it at a fruit shop...

Theres some on ebay.. but you have to buy in bulk and wait for shipping.. heres the link 100x 47nF/50V Radial Ceramic Disc Capacitor Y5V

Will these work Laserov? or do you need the SMD caps?

 

[Tabish]

Well its an electronic component.. don't think your going to find it at a fruit shop...

Theres some on ebay.. but you have to buy in bulk and wait for shipping.. heres the link 100x 47nF/50V Radial Ceramic Disc Capacitor Y5V

Will these work Laserov? or do you need the SMD caps?

Fruit shop! :crackup:

Thanks for the link! That's perfect. Only $1.95 for shipping to Canada too!

EDIT: Hey lazerov, Can you check if those caps are the right type ?


EDIT2: Checked the other thread. laserov said

"You should put additional 47-100nF SMD capacitor between the anode and cathode of the laser diode."

SMD caps are different than these?

 

[bobhaha]

Trying not to thread jack.. so here is a link for every one to use!

100pcs 0805 smd smt chip pcb mount capacitor 473P 47nf


Those are SMD caps.. in a roll LOL they should do the job...

 

[lazerov]

It doesn't matter much which type capacitor you'll use. In fact, I used non-SMD caps like the ceramic disc capacitors on the ebay link when experimenting with this driver. It's not a problem to use them if you have enough space.
The price of the 100pc smd caps is a bit high (I buy them for $0,35/10pc locally in a retail shop which is considered expensive) but $4 is not that much.

 

[Tabish]

It doesn't matter much which type capacitor you'll use. In fact, I used non-SMD caps like the ceramic disc capacitors on the ebay link when experimenting with this driver. It's not a problem to use them if you have enough space.
The price of the 100pc smd caps is a bit high (I buy them for $0,35/10pc locally in a retail shop which is considered expensive) but $4 is not that much.

Got it. Will the ceramic disc cap fit in a aixiz module with the driver?

 

[lazerov]

On the ebay link it is stated that the lead spacing is 2.54mm, so the cap is pretty small. You should have no problems fitting it in an Aixiz module

 

[mfo]

Nice review. Rayfoss is dishonest in my eyes, as they advertise their 405nm LD's as "Blue". Effin scammers...

 

[lazerov]

Thanks mfo!

Yeah, you're right, the category name on their site is "Blue Lasers", which is incorrect. At least most of the lasers are labeled as "blue-violet".

 

[mfo]

Thanks mfo!

Yeah, you're right, the category name on their site is "Blue Lasers", which is incorrect. At least most of the lasers are labeled as "blue-violet".

Yeah. It's just funny how they call it "blue-violet". Anyone that has seen a blu-ray diode in action will agree that they are in no way, shape or form blue. I mean hell, they are 405nm, which is literally right at the edge of the visible spectrum. I believe anything under 400nm is pretty much invisible? (Give or take a couple of nm) Why the hell is the technology even called blu-ray? Some sort of marketing scheme I bet...

 

[bryce007]

just curious, did you toast any diodes with this driver without adding the cap?

 

[lazerov]

just curious, did you toast any diodes with this driver without adding the cap?

I had one running before having any measurements. It was toast not from the spikes, but more likely from severe overdriving :evil:. The driver was outside its rated operating range, too. Current setting resistor was 0.5Ohm => over 200mA.
The reason causing the spikes is that the driver lacks ceramic SMD cap at the output. It has a very small sized, 47uF (tantalum?) capacitor which is definitely not well suited. Small caps with high capacitance typically have high internal resistance. So it just cannot filter the high frequency, short spikes caused by the driver.